Combining multiple optical functions in a single hybrid device can provide systems designers several advantages. First, the insertion loss of a combined device will likely be lower than the summed loss of the equivalent combination of discrete components simply by eliminating the in/out coupling losses of multiple devices. Second, the size of a single hybrid device can generally designed to be smaller than the equivalent combination of discrete components, allowing designers more design flexibility in the size, complexity, and lay-out of system components. Third, the number of fibers in a system can be reduced, again allowing module size reductions as well as minimizing the problems of fiber routing in system components. Finally, inventory management is simplified by reducing the total parts count of an optical system.
The additional complexity of hybrid components, however, can present significant new manufacturing challenges, usually demanding that ever increasing requirements for optical performance, reliability, and cost be met simultaneously. While increasing device complexity (such as the number of internal parts and connecting joints) necessarily increases reliability risks over simpler parts, customers require the same reliability standards for hybrid as for traditional single function devices.
The use of glass tubes and thin sections of epoxy has been used to realize an epoxy-free optical path in passive fiber-optic components, while maintaining simplicity and low cost. This approach has been realized in the use of three or four glass tubes to hold lenses, filters, and isolator cores in devices having up to three optical fiber ports. The devices have been constructed using tubes with perpendicular end faces, and which have been laterally translated to accomplish alignment perpendicular to the beam path, as well as sliding longitudinally to accomplish the focus alignment.
The construction of devices with more than three ports has been difficult using this technique, because the incorporation of a sufficient number of degrees of freedom in the device has seemed to be incompatible with the translational alignment characteristic of the technique.
It is an object of this invention to provide a method of accomplishing angular adjustment between groups of optical elements.
It is a further object to incorporate the flexibility of the solder/collimator construction schemes with the simplicity, low cost, and reliability of the glass tube platform.
Another object of this invention is to provide an improved multi-port optical coupling device.